JP2023079882A - LAMINATED FILM AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Abstract

To provide a laminated film that can reduce the contamination of a production device therefor while having excellent slipperiness.SOLUTION: A laminated film comprises a resin layer (a) comprising a resin (A), and a resin layer (b) provided on at least one principal face of the resin layer (a) and comprising particles and a resin (B). As measured by TPD-MS method under a helium gas, the total amount of gas released from the resin layer (b) when the temperature of the resin layer (b) is raised from 25°C to 280°C at a rate of 10°C/min is 30 wt.ppm or less relative to the weight of the resin layer (b).SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a laminated film and its manufacturing method.

A polarizing plate used in a liquid crystal display device or the like usually includes a polarizer and a polarizer protective film for protecting the polarizer. Patent Documents 1 and 2 disclose polarizer protective films containing fine particles. Patent Documents 3 and 4 describe laminated films in which a surface layer is further laminated on a resin layer containing an ultraviolet absorber.

Japanese Patent No. 3499974 JP 2011-011394 A JP 2005-181615 A WO2020/085326

In order to use the resin film for an optical element such as an image display device, the resin film is required to have few defects such as scratches. The slipperiness of the resin film may be low depending on the type of resin forming the resin film. When a resin film having low slipperiness is wound into a roll, defects such as scratches may increase.
Therefore, the present inventors have found that a resin layer formed of a material containing a resin and particles is laminated on a resin layer in order to improve the slipperiness of the resin film, regardless of the type of resin forming the resin film. We devised a laminated film that

However, in the process of manufacturing such a laminated film by extrusion molding, there have been cases where dirt adheres to manufacturing equipment such as cooling rolls, resulting in deterioration of the quality of the laminated film.

Therefore, there is a demand for a laminated film that can reduce contamination of production equipment while having good slipperiness; and a method for producing a laminated film that can produce such a laminated film.

As a result of intensive studies, the present inventors have found that the dirt adhering to the manufacturing apparatus is caused by a resin layer formed of a material containing a resin and particles, which is laminated on the laminated film. The present inventors have found that the above problems can be solved by using a specific resin layer as the resin layer containing the resin and particles, and completed the present invention.
That is, the present invention provides the following.

[1] A laminate comprising a resin layer (a) containing a resin (A) and a resin layer (b) provided on at least one main surface of the resin layer (a) and containing particles and a resin (B) a film,
The amount of gas released from the resin layer (b) when the resin layer (b) is heated from 25° C. to 280° C. at a rate of 10° C./min, measured under helium gas by the TPD-MS method. A laminated film having a total amount of 30 ppm by weight or less based on the weight of the resin layer (b).
[2] A method for producing a laminated film according to [1],
The manufacturing method is
Step (1) of heating resin (A) to obtain molten resin (A′);
Step (2) of kneading the particles and the resin (B) with a twin-screw extruder;
A step (3) of heating the particles and the resin (B) to obtain a molten resin (B′), and a step of extruding the molten resin (A′) and the molten resin (B′) into layers (4) ), including
In the step (2), venting from the twin-screw extruder,
A method for producing a laminated film.
[3] The step (2) includes kneading the particles and the resin (B) with the twin-screw extruder to obtain a kneaded product of the particles and the resin (B), and the step ( 3) includes heating the kneaded product of the particles and the resin (B) to obtain the molten resin (B′), and the step (3) is performed after the step (2). A method for producing a laminated film according to [2].
[4] The method for producing a laminated film according to [2], wherein the step (2) and the step (3) are performed simultaneously using the same twin-screw extruder.
[5] In any one of [2] to [4], wherein the inner diameter D of the twin-screw extruder and the length Lv from the outlet of the twin-screw extruder to the vent port satisfy the following formula (1) A method for producing the described laminated film.
2<Lv/D≤15 (1)
[6] The method for producing a laminated film according to any one of [2] to [5], wherein the venting is performed at a suction pressure of more than 1 kPa and 100 kPa or less.

ADVANTAGE OF THE INVENTION According to this invention, the laminated|multilayer film which can reduce the contamination of a manufacturing apparatus, and the manufacturing method of the laminated|multilayer film which can manufacture this laminated|multilayer film;

FIG. 1 is a cross-sectional view schematically showing a laminated film according to one embodiment of the invention. FIG. 2 is a cross-sectional view schematically showing a laminated film according to another embodiment of the invention.

Hereinafter, the present invention will be described in detail by showing embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be arbitrarily modified without departing from the scope of the claims of the present invention and their equivalents. The constituent elements of the embodiments shown below can be combined as appropriate. Further, in the drawings, the same components are denoted by the same reference numerals, and the description thereof may be omitted.

In the following description, a "long" film refers to a film having a length of 5 times or more, preferably 10 times or more, with respect to the width, specifically a roll A film that is long enough to be rolled up into a shape and stored or transported. The upper limit of the length of the film is not particularly limited, and can be, for example, 100,000 times or less the width.

[1. Laminated film]
[1.1. Overview of laminated film]
A laminated film according to one embodiment of the present invention includes a resin layer (a) containing a resin (A), and a resin layer (a) provided on at least one main surface of the resin layer (a) and containing particles and a resin (B). When the temperature of the resin layer (b) is increased from 25° C. to 280° C. at a rate of 10° C./min, which is measured under helium gas by the TPD-MS method, the The total amount of gas released from the resin layer (b) is 30 ppm by weight or less based on the weight of the resin layer (b).

In the laminated film, a resin layer (b) containing particles and a resin (B) is provided on at least one main surface of the resin layer (a). The resin layer (b) imparts good slipperiness to the laminated film, regardless of whether it is a layer with high slipperiness or a layer with low slipperiness. As a result, the blocking of the laminated film is reduced, and the occurrence of scratches on the laminated film can be suppressed.

On the other hand, the laminated film tends to contaminate the production equipment more easily than the film without the resin layer (b) containing particles. Although the contamination of the production equipment is not limited to the present invention, it is presumed that the residual solvent contained in the particles contained in the resin layer (b) and the volatile decomposition components generated by heating the particles.

In the laminated film, the total amount of gas released from the resin layer (b) under predetermined conditions is usually 30 ppm by weight or less, preferably 20 ppm by weight or less, more preferably 20 ppm by weight or less, based on the weight of the resin layer (b). is 10 ppm by weight or less, more preferably 5 ppm by weight or less, preferably 0 ppm by weight, but may be 1 ppm by weight or more.

When the total amount of gas released from the resin layer (b) under predetermined conditions is within the above range, contamination of the manufacturing apparatus can be reduced when manufacturing a laminated film with reduced blocking. In particular, when the laminated film is produced by melt extrusion, contamination of rolls for cooling the extruded laminated film can be effectively reduced.

The total amount of gas released from the resin layer (b) can be measured under helium gas by a TPD-MS method (Temperature Programmed Desorption-Mass Spectrometry). The temperature is raised at a rate of 10° C./min, and the total amount of gas released from 25° C. to 280° C. is measured based on the weight of the sample resin layer (b).

The resin layer (b) to be used as a sample can be prepared by peeling off the surface resin layer (b) from the laminated film with a microtome and weighing 1 mg from the peeled resin layer (b).

[1.2. Resin layer (a)]
The resin layer (a) contains resin (A).
Resin (A) is preferably a thermoplastic resin. Thermoplastic resins usually contain a polymer and optionally used optional components.
As the polymer that can be contained in the resin (A), an alicyclic structure-containing polymer is preferable because it can enhance the heat resistance and moisture resistance of the laminated film.

An alicyclic structure-containing polymer refers to a polymer containing an alicyclic structure in its main chain and/or side chain. As the alicyclic structure-containing polymer, an alicyclic structure-containing polymer having an alicyclic structure in its main chain is preferable from the viewpoint of improving the mechanical strength and heat resistance of the laminated film.

Examples of alicyclic structures include saturated alicyclic hydrocarbon (cycloalkane) structures, unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structures, and the like. Among them, a cycloalkane structure and a cycloalkene structure are preferable, and a cycloalkane structure is more preferable, from the viewpoint of mechanical strength and heat resistance.

Although the number of carbon atoms constituting the alicyclic structure is not particularly limited, it is usually 4 or more, preferably 5 or more, and usually 30 or less, preferably 20 or less, more preferably 15 or less. By setting the number of carbon atoms constituting the alicyclic structure within the above range, the mechanical strength, heat resistance and moldability of the laminated film are highly balanced, which is preferable.

The proportion of repeating units containing an alicyclic structure in the alicyclic structure-containing polymer can be appropriately selected depending on the intended use of the laminated film. The proportion of repeating units containing an alicyclic structure in 100% by weight of the alicyclic structure-containing polymer is preferably 55% by weight or more, more preferably 70% by weight or more, and still more preferably 90% by weight or more. , usually not more than 100% by weight. When the proportion of repeating units containing an alicyclic structure in the alicyclic structure-containing polymer is within the above range, the transparency and heat resistance of the laminated film can be effectively improved.

Examples of alicyclic structure-containing polymers include norbornene polymers, monocyclic cyclic olefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and hydrides thereof. mentioned. Among these, norbornene-based polymers and their hydrides are preferable due to their excellent transparency and moldability.

Examples of norbornene-based polymers include ring-opening polymers of monomers having a norbornene structure and hydrides thereof; addition polymers of monomers having a norbornene structure and hydrides thereof. Examples of ring-opening polymers of monomers having a norbornene structure include ring-opening homopolymers of one type of monomer having a norbornene structure, and ring-opening of two or more types of monomers having a norbornene structure. Copolymers, and ring-opening copolymers of monomers having a norbornene structure and arbitrary monomers copolymerizable therewith. Furthermore, examples of addition polymers of monomers having a norbornene structure include addition homopolymers of one type of monomer having a norbornene structure, and addition copolymers of two or more types of monomers having a norbornene structure. and addition copolymers of monomers having a norbornene structure and arbitrary monomers copolymerizable therewith. Examples of these polymers include those disclosed in JP-A-2002-321302.

Specific examples of norbornene-based polymers and hydrides thereof include "Zeonor" manufactured by Nippon Zeon; "Arton" manufactured by JSR; and "TOPAS" manufactured by TOPAS ADVANCED POLYMERS.

The resin (A) may contain one type of alicyclic structure-containing polymer alone, or may contain two or more types of alicyclic structure-containing polymers in combination at any ratio.
From the viewpoint of exhibiting the advantages of the present invention remarkably, the proportion of the alicyclic structure-containing polymer in the resin (A) is preferably 80% by weight or more, more preferably 85% by weight or more, and still more preferably 90% by weight. or more, and usually 100% by weight or less.

The resin (A) may contain optional components other than the polymer as long as the effects of the present invention are not significantly impaired. Examples of optional components include stabilizers such as antioxidants, heat stabilizers and near-infrared absorbers; resin modifiers such as lubricants and plasticizers; coloring agents such as dyes and pigments; The resin (A) may contain one type of optional component alone, or may contain two or more types in combination at any ratio.

Resin (A) may contain an ultraviolet absorber as an optional component. This allows the laminated film to acquire resistance to ultraviolet rays. Therefore, for example, when a laminated film containing an ultraviolet absorber is used as an optical film such as a polarizer protective film, the laminated film and the object to be protected, such as a polarizer protected by this laminated film, are effectively protected from deterioration due to ultraviolet rays. can protect

Examples of UV absorbers that can be used include benzophenone UV absorbers, benzotriazole UV absorbers, acrylonitrile UV absorbers, and hydroxyphenyltriazine UV absorbers. Among them, as ultraviolet absorbers, 2,2′-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol], 2-(2 '-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2,4-di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, 2 ,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)- 5-[(hexyl)oxy]-phenol, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine and the like are preferred. Used. One type of ultraviolet absorber may be used, or two or more types may be used in combination at an arbitrary ratio.

The weight ratio of the ultraviolet absorber in the resin (A) is preferably 1.0% by weight or more, more preferably 3.0% by weight or more, and preferably 23% by weight or less, more preferably 10% by weight or less. is. When the weight ratio of the ultraviolet absorber is at least the lower limit of the above range, ultraviolet rays can be effectively blocked. When the concentration of the ultraviolet absorber is equal to or less than the upper limit of the above range, it is possible to suppress the occurrence of point defects in the laminate film due to poor dispersion of the ultraviolet absorber, and to suppress the decrease in strength of the laminate film.

The thickness of the resin layer (a) can be arbitrarily set according to the intended use of the laminated film. The thickness of the resin layer (a) may be, for example, 1 μm or more and 99 μm or less.

[1.3. Resin layer (b)]
The resin layer (b) contains particles and resin (B).
Resin (B) is preferably a thermoplastic resin. Thermoplastic resins usually contain a polymer and optionally used optional components. Examples of optional components include components similar to the optional components that can be contained in the resin (A).

The polymer that can be contained in resin (B) may be the same as or different from the polymer that can be contained in resin (A). By making the polymer that can be contained in the resin (B) and the polymer that can be contained in the resin (A) the same, the affinity between the resin layer (a) and the resin layer (b) is usually high. , the adhesive strength between the resin layer (a) and the resin layer (b) can be increased.
As the polymer that can be contained in the resin (B), an alicyclic structure-containing polymer is preferable because it can enhance the heat resistance and moisture resistance of the laminated film.

Examples of the alicyclic structure-containing polymer that can be contained in the resin (B) include the same examples and preferred examples of the alicyclic structure-containing polymer that can be contained in the resin (A).

The resin (B) may contain one type of alicyclic structure-containing polymer alone, or may contain two or more types of alicyclic structure-containing polymers in combination at any ratio.
From the viewpoint of exhibiting the advantages of the present invention remarkably, the proportion of the alicyclic structure-containing polymer in the resin (B) is preferably 80% by weight or more, more preferably 85% by weight or more, and still more preferably 90% by weight. or more, and usually 100% by weight or less.

The particles contained in the resin layer (b) may be inorganic particles, organic particles, or composite particles in which an inorganic material and an organic material are combined. The particles contained in the resin layer (b) are also referred to as particles C hereinafter. Particles C may be used singly or in combination of two or more at any ratio.

In one embodiment, the particles C are preferably organic particles, and more preferably organic polymer particles from the viewpoint of facilitating adjustment of the refractive index of the particles and narrowing the spread of the particle size distribution.

Examples of organic polymers that can constitute the particles C include crosslinked copolymers of methyl methacrylate and styrene, and crosslinked polymers containing an alicyclic structure.
From the viewpoint of facilitating adjustment of the refractive index, the particles C are preferably particles of a crosslinked copolymer of methyl methacrylate and styrene.
When the resin (B) contains an alicyclic structure-containing polymer, the particles C are preferably particles of an alicyclic structure-containing crosslinked polymer from the viewpoint of obtaining particles having a refractive index close to that of the resin (B). be.

As mentioned above, the particles C may be particles of a crosslinked copolymer of methyl methacrylate and styrene. Here, the crosslinked copolymer of methyl methacrylate and styrene is a copolymer of methyl methacrylate, styrene, and a crosslinkable monomer. Here, examples of crosslinkable monomers include polyfunctional monomers containing two or more polymerizable groups per molecule. Specific examples include divinylbenzene, ethylene glycol dimethacrylate, 1, 3-butylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, Polyethylene glycol dimethacrylate and tripropylene glycol dimethacrylate are included. The crosslinked copolymer particles can be obtained, for example, by suspension polymerization of a monomer mixture containing methyl methacrylate, styrene, and a crosslinkable monomer. The weight ratio of methyl methacrylate, styrene, and crosslinkable monomers can be set arbitrarily.

As the particles of the crosslinked copolymer of methyl methacrylate and styrene, particles having various average particle sizes are commercially available, and these can be used. Commercially available examples of such particles include "Techpolymer" manufactured by Sekisui Plastics Co., Ltd.

As described above, the particles C may be particles of an alicyclic structure-containing crosslinked polymer. Here, the alicyclic structure-containing crosslinked polymer is a polymer containing a structure in which repeating units containing an alicyclic structure are crosslinked. Examples and preferred examples of the alicyclic structure contained in the alicyclic structure-containing crosslinked polymer, a preferred range of the number of carbon atoms constituting the alicyclic structure, and a preferred range of the proportion of repeating units containing the alicyclic structure are , are the same as the examples and preferred ranges described for the alicyclic structure-containing polymer in the resin (B). When the resin (B) contains an alicyclic structure-containing polymer, the particles C are particles of an alicyclic structure-containing crosslinked polymer so that the refractive index of the particles C is included in the resin layer (b). As the refractive index is close to that of the resin (B) containing the alicyclic structure-containing polymer, the internal haze of the laminated film can be effectively reduced.

Examples of alicyclic structure-containing crosslinked polymers include norbornene crosslinked polymers, monocyclic cyclic olefin crosslinked polymers, cyclic conjugated diene crosslinked polymers, vinyl alicyclic hydrocarbon crosslinked polymers, and These hydrides are mentioned. Among these, norbornene-based crosslinked polymers and their hydrides are preferable because of their good transparency.

Examples of norbornene-based crosslinked polymers include crosslinked polymers of monomer units having a norbornene structure and hydrides thereof; copolymerization of a monomer having a norbornene structure and any monomer copolymerizable therewith combined crosslinked products and hydrides thereof; The copolymer may be a ring-opening copolymer or an addition copolymer of monomers having a norbornene structure.

Examples of the alicyclic structure-containing crosslinked polymer include particles crosslinked by suspension polymerization of a monomer having a norbornene structure in the presence of a crosslinking agent, or a polymer having a norbornene structure with a crosslinking agent. Particles or the like that are crosslinked in the presence can be used.

Particles C may be inorganic particles. Examples of inorganic particles include silica particles, synthetic zeolite particles, and glass particles.
From the viewpoint of uniform particle size distribution, the particles C are preferably silica particles.
Particles of various average particle sizes are commercially available as silica particles, and these can be used. Examples of commercially available products include "QSG" series manufactured by Shin-Etsu Chemical Co., Ltd., "Seahoster" series manufactured by Nippon Shokubai Co., Ltd., and "Admanano" manufactured by Admatechs.

The number average particle diameter of the particles C is preferably 0.10 μm or more, more preferably 0.20 μm or more, and preferably 0.80 μm or less, more preferably 0.50 μm or less. When the number average particle size is at least the lower limit, the laminated film can have sufficient slipperiness. When the number average particle size is equal to or less than the upper limit, the internal haze of the laminated film can be reduced. Further, when the melt containing the resin (B) and the particles C is passed through a polymer filter, clogging of the polymer filter can be reduced. Therefore, a decrease in productivity of the laminated film can be suppressed.

When the particles C are organic particles, the number average particle diameter of the particles C is preferably 0.1 μm or more, more preferably 0.2 μm or more, and preferably 0.8 μm or less, more preferably 0.5 μm or less. be.

When the particles C are inorganic particles, the number average particle diameter of the particles C is preferably 0.1 μm or more, preferably 0.5 μm or less, and more preferably 0.3 μm or less.

The number average particle diameter of the particles C is a value obtained by measuring by a laser diffraction/scattering method using a particle size distribution analyzer.

Particles C preferably have a small volume ratio of coarse particles having a particle diameter of 1 μm or more. As a result, clogging of the polymer filter can be further reduced when the melt containing the resin (B) and the particles C is passed through the polymer filter, thereby further improving the productivity of the laminated film. The volume ratio of coarse particles having a particle diameter of 1 μm or more in the particles C is preferably 1% or less, more preferably 0.1% or less, and usually 0% or more, preferably 0%. 01% or more. Although the upper limit of the particle size of the coarse particles is not particularly limited in terms of calculating the proportion of coarse particles, it can be, for example, 1 mm or less. However, since particles with a particle size of more than 1 mm are completely removed in normal production, even if particles with a particle size of more than 1 mm are included in the calculation, the preferred range of the ratio of coarse particles is the same as the value described above. .
The volume ratio of the coarse particles in the particles C can be reduced by classifying the particles C by sieving or the like to remove the coarse particles.

The refractive index nb of the resin (B) and the refractive index nc of the particles C preferably satisfy the following formula.
|nb−nc|≦0.03
When the refractive index nb and the refractive index nc satisfy the above formula, the internal haze of the laminated film can be further reduced.
The value of |nb-nc| is more preferably 0.02 or less, more preferably 0.01 or less, usually 0 or more, ideally 0, but 0.005 or more. may
The refractive index can be measured with light having a wavelength of 589 nm by the method described in Examples.

In the resin layer (b), the weight ratio of the particles C is preferably 3% by weight or more, more preferably 4% by weight or more, still more preferably 5% by weight or more, and preferably 10% by weight or less, more preferably 9% by weight. % by weight or less, more preferably 8% by weight or less. However, the total weight of particles C and resin (B) is 100% by weight.

When the weight ratio of the particles C in the resin layer (b) is equal to or higher than the lower limit, the laminated film is a long film having a length of more than 2000 m, and when formed into a roll, there is a large amount of Even when a load is applied, the improved slipperiness of the film makes it difficult for blocking to occur near the winding core, and defects such as scratches are less likely to occur.

When the weight ratio of the particles C in the resin layer (b) is equal to or less than the above upper limit, the surface roughness of the resin layer (b) is moderate, and an increase in the external haze of the laminated film is suppressed. As a result, when the laminated film is used as a component of the image display device, the visibility of the image display device can be improved. Moreover, when laminating an optional additional layer such as a hard coat layer on the laminated film, the adhesion between the resin layer (b) and the additional layer is improved. Further, the weight ratio of the particles C in the resin layer (b) is equal to or less than the above upper limit, which is advantageous in terms of production cost. Furthermore, when manufacturing the material for forming the resin layer (b), poor dispersion of the particles C in the resin (B) can be suppressed.

The resin layer (b) may contain an ultraviolet absorber in addition to the resin (B) and the particles C. From the viewpoint of suppressing bleeding out of the ultraviolet absorber, the weight ratio of the ultraviolet absorber to 100 parts by weight of the resin (B) in the resin layer (b) is preferably 2 parts by weight or less, more preferably 1 part by weight or less. and is usually 0 parts by weight or more, may be 0 parts by weight, or may be 0.1 parts by weight or more.

The thickness of the resin layer (b) is preferably 1 μm or more, more preferably 1.5 μm or more, and preferably 5 μm or less, more preferably 3 μm or less.
When the thickness of the resin layer (b) is at least the above lower limit, the thickness can be easily controlled when the resin layer (b) is formed by extrusion molding such as a co-extrusion method. Further, when the thickness of the resin layer (b) is equal to or less than the above upper limit, the slipperiness of the resin layer (b) containing the particles C and the reduction in the strength of the resin layer (b) are balanced, and the strength of the laminated film is increased. In addition, when conveying the laminated film, it is possible to suppress the occurrence of breakage in the laminated film, and to make the laminated film excellent in handleability. Here, when the laminated film has a plurality of resin layers (b), the thickness of each resin layer (b) is preferably within the above range.

The ratio of the thickness of the resin layer (b) to the thickness of the resin layer (a) (thickness of the resin layer (b)/thickness of the resin layer (a)) is preferably 0.32 or less, more preferably 0.25 or less. It is preferably 0.11 or less, and more preferably 0.11 or less. When the ratio is equal to or less than the upper limit, the strength of the laminated film can be improved. The ratio is preferably 0.02 or more, more preferably 0.04 or more. When the ratio is equal to or higher than the lower limit, the thickness of the laminated film can be better controlled. Here, when the laminated film has a plurality of resin layers (b), the thickness of each resin layer (b) is preferably within the above range.

[1.4. Structure of laminated film]
A laminated film according to one embodiment of the present invention has a resin layer (a) and a resin layer (b). The laminated film may be a laminated film consisting of only two layers, the resin layer (a) and the resin layer (b). The laminated film may have any layer in addition to the resin layer (a) and the resin layer (b). The arbitrary layer may be one layer or two or more layers. Moreover, when there are two or more arbitrary layers, the arbitrary layers may be layers having the same thickness, materials, etc., or different layers. The position of any layer can be set arbitrarily. From the viewpoint of thinning the laminated film, it is preferable that the laminated film does not have layers other than the resin layer (a) and the resin layer (b).

The laminated film may have two resin layers (b). When the laminated film has two resin layers (b), the laminated film is usually a laminated film having the resin layer (b), the resin layer (a), and the resin layer (b) in this order, and usually the resin layer ( b) are provided on the two main surfaces of the resin layer (a). It is preferable that the resin layers (b) are arranged on both surfaces of the laminated film so that each of the two resin layers (b) is exposed on both surfaces of the laminated film. When the laminated film has two resin layers (b), they are sometimes referred to as a resin layer (b1) and a resin layer (b2).

The laminated film has two resin layers (b) from the viewpoint of suppressing bleeding out of additives such as ultraviolet absorbers that may be contained in the resin layer (a) and further improving slipperiness. , the first resin layer (b), the resin layer (a), and the second resin layer (b) in this order.

When the laminated film has two resin layers (b), the two resin layers (b) may be made of the same material and may have the same thickness. may be different, and may be composed of materials with different types of components, weight ratios of components, and the like. When the laminated film has two resin layers (b), the two resin layers (b) are preferably made of the same material and are made of the same material, because the production can be facilitated and curling of the laminated film can be suppressed. thickness.

The laminated film may have a plurality of resin layers (a). When the laminated film has a plurality of resin layers (a), each of the plurality of resin layers (a) may be made of materials having different types of components, weight ratios of components, and the like.

Hereinafter, the layer structure of the laminated film according to the embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing a laminated film according to one embodiment of the invention. The laminated film 100 of this embodiment includes a resin layer (a) 110 and a resin layer (b) 120 arranged so as to be in contact with the surface 110U, which is one main surface of the resin layer (a). Resin layer (b) 120 is arranged on the outermost surface of laminated film 100, and surface 120U of resin layer (b) 120 is exposed.

FIG. 2 is a cross-sectional view schematically showing a laminated film according to another embodiment of the invention. The laminated film 200 of this embodiment includes a resin layer (b) 221, a resin layer (a) 210, and a resin layer (b) 222 in this order. Resin layer (b) 221 is arranged so as to be in contact with surface 210U, which is one main surface of resin layer (a) 210 . Resin layer (b) 222 is arranged so as to be in contact with surface 210</b>D, which is the other main surface of resin layer (a) 210 . The resin layer (b) 221 and the resin layer (b) 222 are arranged on the outermost surface of the laminated film 200, respectively, and the surface 221U of the resin layer (b) 221 and the surface 222D of the resin layer (b) 222 are exposed. ing.

[1.5. Thickness, length and characteristics of laminated film]
(thickness)
The thickness of the laminated film can be set to any thickness, preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 80 μm or less.

(Length of laminated film)
The laminated film may be sheet or long. Since the laminated film of the present embodiment can reduce the occurrence of defects such as blocking and scratches near the winding core, it is preferably long and in the form of a roll. When the laminated film is long, the length of the laminated film may exceed 2000 m. The laminated film of the present embodiment reduces the occurrence of defects such as blocking and scratches near the winding core as described above, even when the long film is wound into a roll. can.

(Ultraviolet transmittance)
The laminated film preferably has a low ultraviolet transmittance. The laminate film preferably has a transmittance of 4% or less, more preferably 1% or less, and usually 0% or more, and may be 0%, for ultraviolet light having a wavelength of 380 nm. A laminated film having an ultraviolet transmittance equal to or lower than the upper limit can be suitably used as a protective film for components of image display devices (especially components of organic electroluminescence elements, polarizers, etc.). The ultraviolet transmittance can be measured using a spectrophotometer (eg, "V-7200DS" manufactured by JASCO Corporation).

The UV transmittance of the laminated film can be reduced by including an ultraviolet absorber in any of the layers constituting the laminated film.
Among the layers constituting the laminated film, the resin layer (a) may contain an ultraviolet absorber, the resin layer (b) may contain an ultraviolet absorber, and the resin layer (a) and the resin layer ( Both b) may contain the UV absorber, or any layer other than the resin layer (a) and the resin layer (b) may contain the UV absorber. When the laminated film is a film containing an ultraviolet absorber, it is preferable that the resin layer (a) contains the ultraviolet absorber and the resin layer (b) does not contain the ultraviolet absorber.

(Slipperiness: Coefficient of static friction)
The laminated film has excellent slipperiness. The slipperiness can be evaluated by determining the static friction coefficient of the laminated film with a friction tester under a load of 1 kgf according to JIS K7125. The laminated film preferably has a static friction coefficient of 0.4 or more, preferably 0.8 or less, and more preferably 0.7 or less, as determined by the method described in Examples.

When the static friction coefficient of the laminated film measured under a load of 1 kgf is equal to or higher than the above lower limit, the laminated film has moderate slipperiness and excellent handleability during winding of the laminated film. . In addition, since the static friction coefficient of the laminated film measured under a load of 1 kgf is equal to or less than the upper limit, when the laminated film is made into a roll, such as a long film exceeding 2000 m in length, Even if a large load is applied, blocking near the winding core can be reduced, and defects such as scratches can be reduced.

(internal haze)
A laminated film according to an embodiment of the present invention has a low internal haze.
The internal haze of the laminated film is preferably less than 0.7%, more preferably 0.6% or less, still more preferably 0.5% or less, particularly preferably 0.2% or less, and usually 0.0% or more. and ideally 0.0%. Due to the low internal haze of the laminated film, the laminated film can be suitably used as a component of an image display device that requires fine display performance. The internal haze of the laminated film can be measured using a haze meter.

[2. Laminated film manufacturing method]
"2.1. Outline of manufacturing method of laminated film]
The laminated film can be produced by any method, but is preferably produced by a production method including the following steps (1) to (4).
Step (1): Heating resin (A) to obtain molten resin (A').
Step (2): Kneading particles and resin (B) with a twin-screw extruder.
Step (3): Heating the particles and the resin (B) to obtain a molten resin (B').
Step (4): Extruding the molten resin (A') and the molten resin (B') in layers.
Here, in the step (2), the twin-screw extruder is vented.

The method for producing a laminated film may include optional steps in addition to the steps (1) to (4).

Step (4) is usually performed after steps (1) to (3).
Steps (1) and (3) are preferably performed simultaneously.
Step (3) is usually performed after step (2) or simultaneously with step (2).

Heating of the resin (A) in step (1) can be carried out, for example, by an extruder such as a single-screw extruder or a twin-screw extruder. When the resin (A) contains an optional component such as an ultraviolet absorber in addition to the polymer, the polymer and the optional component are supplied to a twin-screw extruder and kneaded while heating to contain the optional component. Resin (A) may be melted. A molten resin (A') is obtained by the step (1).
The heating temperature in step (1) can be appropriately set depending on the glass transition temperature Tg of the polymer contained in the resin (A) and the weight ratio of optional components such as an ultraviolet absorber that can be contained in the resin (A). The heating temperature in step (1) is preferably Tg + 80°C or higher, more preferably Tg + 90°C or higher, still more preferably Tg + 100°C or higher, preferably Tg + 140°C or lower, more preferably Tg + 130°C or lower, further preferably Tg + 120°C or lower. is. Here, Tg represents the glass transition temperature of the polymer contained in the resin (A). The fluidity of the molten resin (A') can be improved by setting the heating temperature in the step (1) to the above lower limit or higher. Moreover, decomposition of the molten resin (A') can be suppressed by setting the heating temperature to the above upper limit or lower.

The kneading in step (2) is performed with a twin-screw extruder. The twin screw extruder may be any type of twin screw extruder. The twin-screw extruder may be a counter-rotating twin-screw extruder or a co-rotating twin-screw extruder. Preferably.

The twin-screw extruder used in step (2) is equipped with a vent port for venting. The twin-screw extruder may have only one vent port, or may have a plurality of vent ports. A vent port is usually provided on the peripheral surface of the barrel of the twin-screw extruder. By connecting a vacuum device to the vent port, volatile substances can be sucked from the inside of the barrel of the twin-screw extruder. When the twin-screw extruder is provided with a plurality of vent ports, venting may be performed from a plurality of vent ports. Preferably, the twin-screw extruder is provided with only one vent port, and venting is performed from one vent port.

In step (2), venting prevents the manufacturing equipment from being contaminated by residual solvent, resin (B), or volatile decomposition products of particles when the material containing resin (B) and particles is melted and extruded. can be suppressed.

The venting is preferably performed so that the inner diameter D of the twin-screw extruder and the axial length Lv from the outlet of the twin-screw extruder to the vent port satisfy the following formula (1).
2<Lv/D≤15 (1)
The value of (axial length Lv from the outlet of the twin-screw extruder to the vent port)/(axial inner diameter D) is more preferably 3 or more, more preferably 10 or less, and still more preferably 8 or less. .
When the value of Lv/D exceeds 2, suction of the resin (B) from the vent port can be suppressed, and operational stability can be improved. When the value of Lv/D is equal to or less than the upper limit, volatile components contained in the resin (B) can be vented efficiently.

The suction pressure (absolute pressure) of the vent is preferably 100 kPa or less, more preferably 40 kPa or less, still more preferably 30 kPa or less, still more preferably 25 kPa or less, still more preferably 20 kPa or less, preferably more than 1 kPa, more preferably is 5 kPa or more. When the suction pressure is more than 1 kPa, it is possible to suppress the suction of the resin (B) from the vent port and improve the operational stability. When the suction pressure is equal to or lower than the upper limit, volatile components contained in the resin (B) can be vented efficiently.

The heating of the particles and the resin (B) in step (3) can be performed, for example, by an extruder such as a single-screw extruder or a twin-screw extruder.
The heating temperature in step (3) can be appropriately set according to the glass transition temperature Tg of the polymer contained in the resin (B) and the glass transition temperature of the particles. The heating temperature in step (3) is preferably Tg + 80°C or higher, more preferably Tg + 90°C or higher, still more preferably Tg + 100°C or higher, preferably Tg + 140°C or lower, more preferably Tg + 130°C or lower, further preferably Tg + 120°C or lower. is. Here, Tg represents the glass transition temperature of the polymer contained in the resin (B). The fluidity of the molten resin (B') can be improved by setting the heating temperature in the step (3) to the above lower limit or higher. Moreover, decomposition of the molten resin (B') can be suppressed by setting the heating temperature to the above upper limit or lower.

Extruding the molten resin (A') and the molten resin (B') in the step (4) into layers can be performed by a molding method using co-extrusion. Examples of the co-extrusion molding method include a co-extrusion T-die method, a co-extrusion inflation method, and a co-extrusion lamination method, with the co-extrusion T-die method being preferred. Examples of the co-extrusion T-die method include a feed block method and a multi-manifold method, and the feed block method is preferable in terms of simplifying the configuration of equipment.

The molten resin (A') and molten resin (B') extruded in layers in step (4) are usually cooled. Examples of cooling means include cooling rolls. When cooling rolls are used as the cooling means, the extruded molten resin (A') and the molten resin (B') are extruded in layers by casting and conveying them on the cooling rolls, whereby the extruded molten resin (A ') and the molten resin (B') are cooled and solidified to produce a laminated film in which the resin layer (a) and the resin layer (b) are laminated.

The temperature of the cooling roll is preferably Tg-10°C or lower, more preferably Tg-20°C or lower, still more preferably Tg-30°C or lower, and preferably Tg-80°C or higher. Here, Tg represents the glass transition temperature of the polymer contained in the resin (A).

The method for producing a laminated film may include a step of stretching the laminated film extruded in step (4) by any method.
For example, the laminated film may be a film that has undergone any stretching process such as vertical uniaxial stretching, horizontal uniaxial stretching, vertical and horizontal simultaneous biaxial stretching, sequential biaxial stretching, and oblique stretching after step (4). Therefore, the laminated film may be an unstretched film that has not been stretched or a stretched film that has been stretched. The laminated film is preferably an unstretched film. The unstretched film is less likely to disturb the polarization of the image display device, less likely to cause particles to fall off during film production, less likely to cause cohesive failure near the surface layer of the laminated film, and the adhesive strength between the laminated film and other members. can be ensured.

[2.2. First embodiment of method for producing laminated film]
In the method for producing a laminated film according to the first embodiment, the step (2) includes kneading the particles and the resin (B) with the twin-screw extruder to knead the particles and the resin (B). The step (3) includes heating the kneaded product of the particles and the resin (B) to obtain the molten resin (B′), and the step (2) The step (3) is performed later.

In the method for producing a laminated film according to the present embodiment, step (2) and step (3) are not performed at the same time, and step (3) is performed after step (2). In step (2), the twin-screw extruder is vented as described above. Vent conditions may be similar to the preferred conditions described above.

The step (2) may further include a step of forming a kneaded product of the particles obtained by kneading with a twin-screw extruder and the resin (B) into pellets.

In the step (3), examples of the device for heating the kneaded material to obtain the molten resin (B′) include a single-screw extruder and a twin-screw extruder. A single screw extruder is preferred.

In the production method of the present embodiment, venting is performed in the step of obtaining a kneaded product of particles and resin (B), so contamination of the production equipment used in the subsequent steps is effectively reduced, and adhesion to the die port is reduced. It has the advantage of being able to reduce the amount of foreign matter (groin buildup) that may occur.

[2.3. Second embodiment of method for producing laminated film]
In the method for producing a laminated film according to the present embodiment, the step (2) and the step (3) are performed simultaneously using the same twin-screw extruder. That is, in the production method of the present embodiment, particles and resin (B) are supplied to a twin-screw extruder and heated while kneading to form a molten resin (B′) containing particles and a melt of resin (B). get In step (2), the twin-screw extruder is vented as described above. Vent conditions may be similar to the preferred conditions described above.

In the production method of the present embodiment, from the vent port for venting the twin-screw extruder used in steps (2) and (3), in step (4), the molten resin (A ') and the molten resin (B ') is preferably 4 hours or less, more preferably 2 hours or less, and usually greater than 0 hours.
When the average residence time is equal to or less than the above upper limit, decomposition of the resin (B) and particles can be effectively suppressed.

In the production method of the present embodiment, venting is performed in the step of heating the particles and the resin (B) to obtain the molten resin (B′), so the volatile impurities generated before the extrusion step can be efficiently removed. It has the advantage of being able to reduce the amount of foreign matter (deposit) adhering to the die opening.

[3. Application of laminated film]
The laminated film has good slipperiness and reduced defects such as scratches. Therefore, it can be suitably used as an optical film such as a polarizer protective film.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples shown below, and can be arbitrarily modified without departing from the scope of the claims of the present invention and their equivalents.

In the following description, "%" and "parts" representing amounts are by weight unless otherwise specified. In addition, unless otherwise specified, the operations described below were performed under normal temperature (20° C.±15° C.) and normal pressure (1 atm) conditions.

[Evaluation method]
(Measurement of resin layer (b) outgas amount by TPD-MS method)
The resin layer (b1) was peeled off from the laminated film with a microtome. 1 mg was weighed out from the peeled resin layer (b1). A weighed sample of the resin layer (b1) was set in a mass spectrometer equipped with a heating device. The mass spectrometer is equipped with a TRC heating device as a heating device, and a Shimadzu Corporation "GCMS-QP2020(14)" as a mass spectrometer.
The carrier gas (helium) was kept flowing in the measurement chamber for 15 minutes or more before heating the sample. Next, the sample was heated from room temperature (25°C) to 400°C at a heating rate of 10°C/min, and mass spectrometric measurement of the generated gas was performed. of total weight was obtained.
Mass spectrometry conditions were as follows.
・MS sensitivity Gain 1.60kV
・Mass number range m/z = 10 to 300
・Atmosphere Helium flow (50 mL/min)
The ratio of the total weight of gas released from the sample during heating from room temperature to 280° C. to the weight of the weighed sample (weight ppm) was calculated.

(thickness of each layer of film)
The film was sliced to a thickness of 0.05 μm using a microtome (“RV-240” manufactured by Yamato Koki Co., Ltd.), and the cross section was observed under a microscope to measure the thickness of each layer.

(Glass transition temperature of resin)
The glass transition temperature of the resin was measured by differential scanning calorimetry using Hitachi's "DSC7020". The measurement was performed in a nitrogen atmosphere at a temperature elevation rate of 20° C./min and a holding time of 30 min.

(refractive index)
The refractive index of resin or particles was measured by the Becke method (JIS K7142). The refractive index was measured by immersing the resin pellets or particles in a liquid with a known refractive index and checking the outline of the resin pellets or particles. A sodium D line with a wavelength of 589 nm, which is monochromatic light, was used as the light source of the microscope.

(Number average particle diameter of particles)
The number average particle size of particles was measured by the following method.
A water slurry with a particle concentration of 2% by weight was prepared, and measured by a laser diffraction/scattering method using Seishin Enterprise Co., Ltd.'s "LMS-3000".

(Roll contamination)
The time from the start of production of the laminated film to the start of contamination of the chill roll was measured.
The presence or absence of roll contamination was determined according to the following procedure, based on the number of uneven defects transferred to the laminated film due to contamination.
(procedure)
The laminated film was cut to a length of 1.5 m, and the projector, laminated film, and screen were arranged in this order, and projection inspection was performed.
As a projector used for projection, "S-light" manufactured by Nippon Gijutsu Center was used.
The distance between the projector and the laminated film was 2300 mm.
The distance between the laminated film and screen was 200 mm.
The height of the unevenness of the laminated film detected by this method is measured with a Zygo laser interferometer, and if the height of the unevenness exceeds 300 nm and exceeds ¹ /m2, the roll is contaminated. I decided.

(Static friction coefficient of film)
Using a friction tester ("TR-2" manufactured by Toyo Seiki Seisakusho), the static friction coefficient of the film obtained in each example was measured according to JIS K7125. The measurement was performed under the conditions of a test piece size of 140 mm×65 mm, a load of 1 kgf, and a speed of 500 mm/min. The smaller the coefficient of static friction, the greater the slidability of the film.

[Example 1]
(Preparation of material for resin layer (a))
Nippon Zeon Co., Ltd. "Zeonor 1600" (glass transition temperature 160 ° C., refractive index 1.53) 95 parts by weight, UV absorber (2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol]) with 5 parts by weight, a co-rotating twin-screw extruder (manufactured by Japan Steel Works, Ltd.) TEX-44αII", inner diameter DΦ=25 mm, barrel length L/D=42) and kneaded at a kneading temperature of 260° C. to obtain resin (A) for resin layer (a).
The resin (A) was extruded from a twin-screw extruder in the form of a strand and molded by a pelletizer to obtain pellets of the resin (A). "Zeonor 1600" is a resin containing an alicyclic structure-containing polymer (norbornene-based polymer). "ADEKA STAB LA-31" is a benzotriazole-based UV absorber.

(Preparation of materials for resin layer (b1) and resin layer (b2): kneading step)
Nippon Zeon Co., Ltd. "Zeonor 1600" (glass transition temperature 160 ° C., refractive index 1.53) as resin (B) 95 parts by weight, and Sekisui Plastics Co., Ltd. polymer beads "Techpolymer" (particle C) Number average particle diameter 0.5 μm, refractive index 1.53) and 5 parts by weight, a co-rotating twin-screw extruder with a vent port (“TEX-44αII” manufactured by Japan Steel Works, Ltd., inner diameter DΦ = 25 mm, barrel Length L / D = 42), kneaded at a kneading temperature of 270 ° C. while venting from the vent port at a suction pressure of 20 kPa (absolute pressure), and a kneaded product of particles and resin (B) (resin (B ')). The value obtained by dividing the axial length Lv from the outlet of the twin-screw extruder to the vent port for venting by the inner diameter D of the twin-screw extruder (Lv/D) was 3.
The resin (B') was extruded in a strand from a twin-screw extruder and molded with a pelletizer to obtain resin (pr) pellets for the resin layer (b1) and the resin layer (b2).
"Techpolymer" is a microparticle of a crosslinked copolymer of methyl methacrylate and styrene. The absolute value of the difference (|nb-nc|) between the refractive index nb of the resin (B) and the refractive index nc of the particles C is zero.

(Production of laminated film: extrusion process of molten resin (A') and molten resin (B'))
A laminated film was produced by co-extrusion using a two-kind three-layer multi-layer extruder (manufactured by Shibaura Kikai Co., Ltd.) having a feed block. The feed block has a structure capable of forming a laminate having a three-layer structure of resin layer (b1)/resin layer (a)/resin layer (b2). In the feed block, a first single-screw extruder for melting a resin for forming a resin layer (a) to obtain a molten resin (A') and extruding it, and a resin layer (b1) and a second single-screw extruder for melting the resin for forming the resin layer (b2) to obtain the molten resin (B') and for extruding this. Pellets of the resin (A) are supplied to the first single screw extruder as the resin for the resin layer (a), and the resin is fed to the second single screw extruder as the resin for the resin layer (b1) and the resin layer (b2). (pr) pellets were fed. A laminated film having a resin layer (b1), a resin layer (a), and a resin layer (b2) in this order is obtained by discharging and cooling the laminated molten resin from a die connected to a feed block onto a cooling roll. rice field. The resin temperature in the extrusion process was set at 265°C, and the temperature of the cooling roll was set at 130°C. Extrusion conditions were adjusted so that the thickness of each of the resin layer (b1) and the resin layer (b2) was 2 μm, the thickness of the resin layer (a) was 36 μm, and the total thickness of the laminated film was 40 μm.

The obtained laminated film was evaluated by the method described above.

[Example 2]
A laminated film was produced by co-extrusion using a two-kind three-layer multi-layer extruder (manufactured by Shibaura Kikai Co., Ltd.) having a feed block. The feed block has a structure capable of forming a laminate having a three-layer structure of resin layer (b1)/resin layer (a)/resin layer (b2). In the feed block, a first twin-screw extruder (“TEM-41SS” manufactured by Shibaura Machine Co., Ltd., inner diameter DΦ = 41 mm, barrel length L / D = 42), and a second twin-screw extruder with a vent port ("TEM- 41SS" inner diameter DΦ=41 mm, barrel length L/D=42) are connected.

(Kneading melt extrusion process)
95 parts by weight of "Zeonor 1600" (glass transition temperature 160 ° C., refractive index 1.53) manufactured by Nippon Zeon Co., Ltd. as an alicyclic structure-containing resin, and 5 parts of an ultraviolet absorber (ADEKA "ADEKA STAB LA-31"). were supplied to a first twin-screw extruder, kneaded and melted at a temperature of 260° C., and the obtained molten resin (molten resin (A′)) was supplied to a feed block.
As the resin (B), 95 parts by weight of "Zeonor 1600" (glass transition temperature 160 ° C., refractive index 1.53) manufactured by Nippon Zeon Co., Ltd., which is an alicyclic structure-containing resin, and Sekisui Plastics Co., Ltd. as particles C 5 parts by weight of polymer beads "Techpolymer" (number average particle diameter 0.5 μm, refractive index 1.53) are supplied to the second twin-screw extruder, and the suction pressure is 25 kPa (absolute pressure ), the mixture was kneaded and melted at a kneading temperature of 270° C., and the obtained molten resin (molten resin (B′)) was supplied to the feed block. The value obtained by dividing the axial length Lv from the outlet of the second twin-screw extruder to the vent port for venting by the inner diameter D of the twin-screw extruder (Lv/D) was 3.
The absolute value of the difference (|nb-nc|) between the refractive index nb of the resin (B) and the refractive index nc of the particles C is zero.

A laminated film having a resin layer (b1), a resin layer (a), and a resin layer (b2) in this order is obtained by discharging and cooling the laminated molten resin from a die connected to a feed block onto a cooling roll. rice field. The resin temperature in the extrusion process was set at 265°C, and the temperature of the cooling roll was set at 130°C. Extrusion conditions were adjusted so that the thickness of each of the resin layer (b1) and the resin layer (b2) was 2 μm, the thickness of the resin layer (a) was 36 μm, and the total thickness of the laminated film was 40 μm. Further, the extrusion conditions were adjusted so that the average residence time of the resin from the vent port of the second twin-screw extruder to the die to the vent was 4 hours.

The obtained laminated film was evaluated by the method described above.

[Example 3]
Extrusion conditions were adjusted so that the average residence time of the resin from the vent port of the second twin-screw extruder to the die to the vent was 2 hours. A laminated film was obtained in the same manner as in Example 2 except for the above matters. The obtained laminated film was evaluated by the method described above.

[Comparative Example 1]
In (preparation of materials for resin layer (b1) and resin layer (b2)), venting was not performed from the vent port of the twin-screw extruder. A laminate film was obtained in the same manner as in Example 1 except for the above matters. The obtained laminated film was evaluated by the method described above.

[result]
Table 1 shows the results.
In Table 1, abbreviations have the following meanings.
"ZNR1600": "Zeonor 1600" manufactured by Nippon Zeon Co., Ltd.
"UVA": UV absorber ("ADEKA STAB LA-31" manufactured by ADEKA)
"Particle C": polymer beads "Techpolymer" manufactured by Sekisui Plastics Co., Ltd.
"Lv/D": A value obtained by dividing the axial length Lv from the outlet of the twin-screw extruder to the vent port for venting by the inner diameter D of the twin-screw extruder

From the above results, the laminated films of Examples 1 to 3, in which the outgassing amount of the resin layer (b) was 30 ppm by weight or less, measured under predetermined conditions, had a low coefficient of static friction and good slip properties. Nevertheless, roll contamination is reduced.
In addition, the laminated film of Comparative Example 1 has a large degree of contamination of the roll.

100 Laminated film 110 Resin layer (a)
110U face 120 resin layer (b)
120U surface 200 laminated film 210 resin layer (a)
210U surface 210D surface 221 resin layer (b)
221U surface 222 resin layer (b)
222D surface

Claims (6)

A laminated film comprising a resin layer (a) containing a resin (A) and a resin layer (b) provided on at least one main surface of the resin layer (a) and containing particles and a resin (B). hand,
The amount of gas released from the resin layer (b) when the resin layer (b) is heated from 25° C. to 280° C. at a rate of 10° C./min, measured under helium gas by the TPD-MS method. A laminated film having a total amount of 30 ppm by weight or less based on the weight of the resin layer (b). A method for producing a laminated film according to claim 1,
The manufacturing method is
Step (1) of heating resin (A) to obtain molten resin (A′);
Step (2) of kneading the particles and the resin (B) with a twin-screw extruder;
A step (3) of heating the particles and the resin (B) to obtain a molten resin (B′), and a step of extruding the molten resin (A′) and the molten resin (B′) into layers (4) ), including
In the step (2), venting from the twin-screw extruder,
A method for producing a laminated film. The step (2) includes kneading the particles and the resin (B) with the twin-screw extruder to obtain a kneaded product of the particles and the resin (B), and the step (3) , wherein the kneaded product of the particles and the resin (B) is heated to obtain the molten resin (B'), and the step (3) is performed after the step (2). The method for producing the laminated film according to 1. 3. The method for producing a laminated film according to claim 2, wherein the step (2) and the step (3) are performed simultaneously by the same twin-screw extruder. The laminated film according to any one of claims 2 to 4, wherein the inner diameter D of the twin-screw extruder and the length Lv from the outlet of the twin-screw extruder to the vent port satisfy the following formula (1). Production method.
2<Lv/D≤15 (1) The method for producing a laminated film according to any one of claims 2 to 5, wherein the venting is performed at a suction pressure of more than 1 kPa and 100 kPa or less.

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